It is sometimes necessary to form a feature or features in a nonphotoimagable material 102 deposited on a substrate 100 (see FIGS. 1 and 2). One way to do this is by first depositing the nonphotoimagable material on the substrate, and then mechanically removing portions of the nonphotoimagable material (e.g., by means of sandblasting) to define the feature 104 or features therein. However, removing portions of a nonphotoimagable material in this way almost always results in removal of some of the substrate. For some applications, this is acceptable. For instance, if a channel 200 needs to be formed in the substrate, and it is desired that the nonphotoimagable material be registered to the edges of the channel, then it may be acceptable to deposit the nonphotoimagable material on the substrate and then sandblast through both the nonphotoimagable material and the substrate until the channel is formed in the substrate. In other applications, the removal of substrate material is not necessary, or even undesirable. In these applications, the above-described method for removing portions of a nonphotoimagable material from a substrate can be problematic.
The above-described method can also be problematic due to adverse reactions between the removal means (e.g., a sandblasting machine) and the substrate. For instance, if the substrate is metallic, sandblasting its surface might result in electrostatic discharge which tends to blacken the substrate or nonphotoimagable material or, in a worse case scenario, even melt or vaporize the nonphotoimagable material.
The above-described method can also be problematic when a feature to be formed in a nonphotoimagable material lies above an existing substrate feature. For example, if a feature to be formed in a nonphotoimagable material lies above 1) a thin layer of material that has already been deposited on a substrate, 2) a layer of carefully controlled thickness that has already been deposited on the substrate, or 3) a component or other feature that has already been formed in, or deposited on, the substrate, then any blasting of (or xe2x80x9cblast throughxe2x80x9d) such a feature would likely be undesirable.
Finally, even when it might be acceptable to deposit a nonphotoimagable material on a substrate and then remove portions of the nonphotoimagable material along with portions of the substrate, there might be later manufacturing steps which make the timing of such deposition and feature formation impractical. For example, consider a need to thermally or chemically treat (e.g., anneal or etch) a substrate channel that is formed after the nonphotoimagable material is deposited on the substrate. If the nonphotoimagable material cannot withstand the thermal or chemical treatment, then depositing it on the substrate prior to formation and treatment of the substrate channel would be undesirable.
One aspect of the invention is embodied in a method for forming a feature in a nonphotoimagable material deposited on a substrate. The method comprises depositing a first resist on at least a portion of the substrate that will underlie the feature in the nonphotoimagable material. The nonphotoimagable material is then deposited so that it overlaps at least a portion of the first resist. Thereafter, a second resist is deposited on at least a portion of the nonphotoimagable material, and the feature is patterned on the second resist. The part is then sandblasted until the first resist is exposed. After sandblasting, the first and second resists are removed.
Another aspect of the Invention is embodied in a method for protecting an existing feature on a substrate while forming a new feature in a nonphotoimagable material deposited on the substrate. The method comprises depositing a first resist on at least a portion of the existing feature that will underlie the new feature. The nonphotoimagable material is then deposited so that it overlaps at least a portion of the first resist. Thereafter, a second resist is deposited on at least a portion of the nonphotoimagable material, and the new feature is patterned on the second resist. The part is then sandblasted until the first resist is exposed. After sandblasting, the first and second resists are removed.
Yet another aspect of the invention is embodied in a switch. The switch is produced by forming at least one channel in a channel plate then depositing a first resist on at least a portion of a channel that will underlie a feature that is to be formed in a nonphotoimagable material. The nonphotoimagable material is then deposited so that it overlaps at least a portion of the first resist. Thereafter, a second resist is deposited on at least a portion of the nonphotoimagable material, and the feature is patterned on the second resist. The channel plate is then sandblasted until the first resist is exposed. After sandblasting, the first and second resists are removed. Finally, the at least one channel formed in the channel plate is aligned with at least one feature on a substrate, and at least a switching fluid is sealed between the channel plate and the substrate by means of the nonphotoimagable material.
Other embodiments of the invention are also disclosed.